Weather Types and Hourly to Multiday Rainfall Characteristics in Tropical Australia
Weather Types and Hourly to Multiday Rainfall Characteristics in Tropical Australia
复制标题
DOI：
10.1175/jcli-d-18-0384.1
复制
发表时间：
2019-07-01
影响因子：
4.9
通讯作者：
Fowler, Hayley J.
中科院分区：
文献类型：
--
作者：
Moron, Vincent;Barbero, Renaud;Fowler, Hayley J.
使用 850 hPa 每小时 6 小时低层风的聚类分析，计算了热带澳大利亚雨季（1979 年 11 月至 2015 年 3 月）的六种天气类型 (WT)。 WT可以被解释为在不同时间尺度上运行的至少五种不同现象的不同组合：昼夜循环、快速和反复出现的大气现象（例如瞬态低压）、季节内马登-朱利安振荡、年度循环以及主要与厄尔尼诺-南方涛动相关的年际变化。 WT 也强烈锁相到季风的中断/活跃阶段；两个季风风潮主要表征季风开始和结束时或季风中断期间盛行的信风状况，而三个季风风潮主要发生在其核心阶段和活跃阶段。 WT 对湿期频率的影响最强，而对强度的影响则根据降雨的时间聚集而变化。在每小时的时间尺度上，季风湿地的气候平均湿润强度在空间上趋于接近恒定，并且与其他湿地相比，季风湿地的气候平均湿润强度并没有系统性地更大。然而，一种过渡性WT，在11月下旬左右最普遍，其特点是天气强迫较弱，总体条件比季风WT更干燥，与一些站点（包括约克角半岛内部）每小时高降雨强度数量的增加有关。当时间聚合超过 6-12 小时时，某些季风 WT 的平均强度往往较大，这与更频繁且稍长的湿润期相关。
Six weather types (WTs) are computed for tropical Australia during the wet season (November-March 1979-2015) using cluster analysis of 6-hourly low-level winds at 850 hPa. The WTs may be interpreted as a varying combination of at least five distinct phenomena operating at different time scales: the diurnal cycle, fast and recurrent atmospheric phenomena such as transient low pressure, the intraseasonal Madden-Julian oscillation, the annual cycle, and interannual variations mostly associated with El Nino-Southern Oscillation. The WTs are also strongly phase-locked onto the break/active phases of the monsoon; two WTs characterize mostly the trade-wind regime prevalent either at the start and the end of the monsoon or during its breaks, while three monsoonal WTs occur mostly during its core and active phases. The WT influence is strongest for the frequency of wet spells, while the influence on intensity varies according to the temporal aggregation of the rainfall. At hourly time scale, the climatological mean wet intensity tends to be near-constant in space and not systematically larger for the monsoonal WTs compared to other WTs. Nevertheless, one transitional WT, most prevalent around late November and characterized by weak synoptic forcings and overall drier conditions than the monsoonal WTs, is associated with an increased number of high hourly rainfall intensities for some stations, including for the interior of the Cape York Peninsula. When the temporal aggregation exceeds 6-12 h, the mean intensity tends to be larger for some of the monsoonal WTs, in association with more frequent and also slightly longer wet spells.